Between one-third and one-half of employees participate directly in company performance through profit sharing, gainsharing, employee ownership, or stock options. This flies in the face of concerns about the free rider problem and worker risk aversion in group incentives, and raises many questions about the effects on firms and workers. This paper lays out the major reasons we may see such "shared capitalism" plans, and reviews recent nationally representative surveys on the prevalence of these plans. We also introduce the NBER shared capitalism data, based on questions added to the 2002 and 2006 General Social Surveys (GSS) and more than 40,000 employee surveys from 14 companies with different combinations of shared capitalism plans. We find that while shared capitalism exists broadly ...